From e37dbce2f7d22c8cbc4d576c55b41e73aec28fd4 Mon Sep 17 00:00:00 2001
From: Joey Parrish <joeyparrish@google.com>
Date: Tue, 14 Apr 2015 14:32:27 -0700
Subject: [PATCH] Change underflow system in Player.

Underflow is now possible before the playhead enters a gap in the
buffered ranges.  Some misbehaving live content freezes with as much
as 50ms of data still buffered, so going into an underflow/buffering
state with a positive amount of buffered data is desirable.

To keep this from causing trouble at EOF, there is a special check
against video.duration.

Change-Id: I5a350c543fe33910a55cd8e9ebd8fd1ab2d6408c
---
 lib/player/player.js | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/lib/player/player.js b/lib/player/player.js
index 3ff08769d..b794e7765 100644
--- a/lib/player/player.js
+++ b/lib/player/player.js
@@ -844,18 +844,21 @@ shaka.player.Player.prototype.onWatchdogTimer_ = function() {
   // buffering.  |buffered| will show the intersection of buffered ranges for
   // both audio and video, so this is an accurate way to sense that we are
   // buffering.  The 'stalled', 'waiting', and 'suspended' events do not work
-  // for this purpose as of Chrome 38.
+  // for this purpose as of Chrome 38.  Nor will video.readyState.
   var bufferEnd = buffered.length ? buffered.end(buffered.length - 1) : 0;
-  var underflow = this.video_.currentTime - bufferEnd;
+  var buffered = bufferEnd - this.video_.currentTime;
+  var threshold = shaka.player.Player.UNDERFLOW_THRESHOLD_;
+  var fudgedBufferEnd = bufferEnd + shaka.player.Player.BUFFERED_FUDGE_FACTOR_;
 
   if (!this.buffering_) {
-    if (underflow > shaka.player.Player.UNDERFLOW_THRESHOLD_) {
+    // Don't go into a buffering state at the end of the video.
+    if (fudgedBufferEnd < this.video_.duration && buffered < threshold) {
       this.enterBufferingState_();
     }
   } else {
     var resumeThreshold = this.videoSource_.getResumeThreshold();
     shaka.asserts.assert(resumeThreshold > 0);
-    if (underflow < -resumeThreshold) {
+    if (buffered > resumeThreshold) {
       this.endBufferingState_();
       this.video_.play();
     }
@@ -864,13 +867,23 @@ shaka.player.Player.prototype.onWatchdogTimer_ = function() {
 
 
 /**
- * The threshold for underflow, in seconds.  If the play head is outside the
- * buffered range by this much, we will consider the player to be out of data.
+ * The threshold for underflow, in seconds.  If there is less than this amount
+ * of data buffered, we will consider the player to be out of data.
  *
  * @private {number}
  * @const
  */
-shaka.player.Player.UNDERFLOW_THRESHOLD_ = 0.050;
+shaka.player.Player.UNDERFLOW_THRESHOLD_ = 0.1;
+
+
+/**
+ * A fudge factor applied to buffered ranges to determine if the end of the
+ * video is buffered.
+ *
+ * @private {number}
+ * @const
+ */
+shaka.player.Player.BUFFERED_FUDGE_FACTOR_ = 0.05;
 
 
 /**